Variables.

The Crystal Empire came back much earlier than what it 'should' have. Sombra recovered much faster than he 'should' have. Cadence and Shining Armor were delayed. Sombra was so much more powerful than anticipated.

Trixie spent ten years of her life in hell on Equestria, imprisoned for many of them. Her body, wracked by disease, nearly gave out on her... but the Elements of Harmony would not be denied, for they are the most powerful form of magic known to ponydom. A contract, a stay of death, a rescue and escape, and an attempt at rebellion. Love.

Loss.

One final contract. To earn back her life, Trixie's mind was to travel back in time and stop Sombra before he had the opportunity to kill Twilight Sparkle. Saving the others was a good thing, but the world literally depended on her survival.

With her healthy body back, free of Sombra's spells and... brands, with the strength of so much time spent on a rock farm, and with the training she received, it was disappointingly easy.

The problems started when the refugees arrived.

Turns out, her old timeline sent a few messages along with her.

Inspired by the many 'X beats Sombra before time' fics floating around.

With a little bit of 'Days of Future Past' thrown in, because I was itching for some even before seeing the movie.